Ancient tribes, military, trade and China's rise meet on this island

Shompen people shun the outside world and live in the dense forest on Great Nicobar Island. (Anthropological Survey of India)

Bulldozers are tearing through ancient forests home to some of the last remaining isolated people on Earth.

Championed by Indian Prime Minister Narendra Modi, the ambitious $12.5 billion Great Nicobar Island Project in the eastern Indian Ocean is forging ahead, designed to counter China's regional rise, bolster military capability and capitalise on trade.

Mr Modi said last year the project was "of strategic, defence and national importance" and would transform the region into a "major hub of maritime and air connectivity".

The three-phase project has been planned for years and is expected to be completed by 2047, with phase one set to be completed by 2035.

Preliminary works are believed to have started last year, however concerns remain for one of the last largely uncontacted tribes on Earth and the endemic species that rely on the island's delicate ecosystem.

Here's what we know about the island, the Shompen people, the project and concerns surrounding it.

The island is part of an archipelago in the Andaman Sea, in the Indian Ocean, sitting roughly 40 nautical miles from the Strait of Malacca.

About 30 per cent of global trade passes through the strait, including significant amounts of China's oil and gas supplies.

The island is home to roughly 9,000 people, including 1,200 from indigenous groups including the Nicobarese and the Shompen.

Indigenous rights organisation Survival International says the 300 or so Shompen are hunter-gatherers who shun contact with the outside.

It estimates they have been on the island for some 10,000 years.

It says the Nicobarese on the island live in communal houses of between 20 and 30 people, and are better integrated with settler communities.

Very few Shompen have contact with their Nicobarese neighbours or the outside world, with permits required from local island authorities to visit them.

Great Nicobar Island is also home to dozens of endemic species according to UNESCO, and a nesting spot for the endangered leatherback turtle, the largest sea turtle in the world.

Roughly 95 per cent of the 910 square kilometre island is forest, with much of the island's coast encircled by lagoons and coral reefs.

The island's waters and forests are home to species found nowhere else in the world. (R.Satish Babu/AFP)

Nearly one fifth of the island will be cleared for the massive project.

The government estimates some 711,000 trees will be cleared, but some conservationists put the number in th